Off the Deep End – 10 Challenging Observing Projects

by Steve Gottlieb


Originally hosted on the The SF Bay Area Astronomy Connection (TAC) website, restored using the WayBackMachine archival, reformatted and edited by Akarsh Simha. This article was the basis of a talk given by Steve Gottlieb at the 2007 Golden State Star Party.


Sharpless HII regions Extragalactic Globulars Palomar/Obscured Globulars Local Group Dwarf Galaxies Compact galaxy groups
Arp interacting pairs Abell Galaxy Clusters HII regions in External Galaxies Ancient, Giant Planetaries Quasars

1) Sharpless HII regions

Object RA Dec Size Mag Const Notes
Sh 2-11 17 24.7 -34 12 50x40   Sco Brightest section of NGC 6357 is an elongated strip with a close double at S edge.
Faint open cluster Pismis 24 to S.
Sh 2-84 19 49.0 +18 23 15x3   Sge "Little California Nebula" is a faint, 4’ shallow arc between 2 mag 8.5 stars.
Located 25’ ESE of mag 3.7 Delta Sagittae.
Sh 2-105 20 12.1 +38 21 20x10   Cyg Crescent Nebula (NGC 6888) is a huge 18’x11’ oval, with knots and tendrils, in a rich Cygnus star field. Use OIII filter.
Sh 2-108 20 22.2 +40 15     Cyg IC 1318 is an extremely large and faint HII complex surrounding Gamma Cyg.
Use very low x and H-beta or UHC filter.
Sh 2-112 20 33.9 +45 39 9x7   Cyg Very irregular, relatively easy HII region, 10’ diameter, surrounding mag 9 star.
Sh 2-117 20 59.3 +44 31 120x100   Cyg Use low x & OIII filter to view the North American nebula.
Highest contrast around "Gulf of Mexico" and "Baja" region
Sh 2-125 21 53.5 +47 16 12x12   Cyg The Cocoon Nebula (IC 5146) is a large, milky glow surrounding 2 mag 9 stars.
Use a H-beta filter.
Sh 2-132 22 19.1 +56 05 30x20   Cep With an OIII filter this huge HII region appears roughly 20’x15’, elongated E-W.
Sh 2-157 23 16.0 +60 28 60x50   Cas Huge, faint curving arc, ~35’x8’, extended N-S.
Open cluster Mrk 50 off W side. Use OIII filter.
Sh 2-162 23 20.7 +61 12 15x8   Cas The Bubble Nebula (NGC 7635) is a low surf br HII region, curves mostly north of a mag 8.5 star. Located 35’ SW M52.

Further Reading

2) Extragalactic Globulars

Object RA Dec Size Mag Const Notes
WLM-1 00 01.8 -15 28     Cet The brightest gc in the Wolf-Lundmark-Melotte system is a mag 16 "star" on the W side of the galaxy.
M31-G1 00 32.8 +39 35 10" 13.7 And Brightest gc in M31, 2.5° SW of center.
Out of focus "star" forming a small triangle with 2 mag 12/13 stars.
M31-G78 00 41.0 +41 14 3.2" 14.2 And "Soft" mag 14.5 star located 30’ W of the core of M31.
This gc is the 2nd or 3rd brightest in M31.
M31-G76 00 41.0 +40 36 3.6" 14.3 And Visible as a mag 14.2 "star" in a small "W" asterism and near the SW tip of M31.
Similar brightness to G78 above.
M33-C39 01 34.8 +30 22   15.9 Tri Brightest gc in M33 though only 16th mag and stellar.
Needs a finder chart to pin down location.
NGC 1049 02 39.8 -34 15 1.3 12.6 For This small 12th magnitude gc is the brightest of 5 in the Fornax Dwarf.
Fornax-4 02 40.1 -34 32 0.8 13.6 For Third brightest gc in the Fornax Dwarf, roughly mag 13.5 and very small.
Fornax-5 02 42.3 -34 06 1.0 13.4 For Second brightest gc in the Fornax Dwarf and similar to Fornax-4.

Further Reading

3) Palomar/Obscured Globulars

Object RA Dec Size Mag Const Notes
Palomar 5 15 16.1 -00 07 6.9 11.8 Ser Extremely low surface brightness gc located 30’ south of mag 5.6 4 Serpentis.
Djorgovski 2 18 01.8 -27 50 3.5 9.9 Sgr Recently discovered gc just 21’ WNW of open cluster NGC 6520 and dark nebula B86!
Palomar 7 18 10.7 -07 12 7 10.3 Ser IC 1276 is an irregular 3’ glow with a mag 13.5 star at the W edge. Has a mottled, patchy appearance.
Palomar 8 18 41.5 -19 50 4.7 11.2 Sgr One of the easier Palomar globulars, roughly 2’ in diameter.
A large scope may partially resolve.
Palomar 9 18 55.1 -22 42 3.9 9.2 Sgr NGC 6717 is a small, faint glow easy to locate just 2’ S of mag 5 Nu 2 Sagitarii!
Terzan 7 19 17.7 -34 40 2.6 12 Sgr Low surf br glow with no central concentration.
This gc may have been a member of the Sagittarius Dwarf Spheroidal gx
Arp 2 19 28.7 -30 21 2.5 12.3 Sgr Extremely low surf br glow, 2’ diameter in a rich star field.
Very difficult to pick out.
Terzan 8 19 41.7 -34 00 5.0 12.4 Sgr Very faint, round glow, just 1.0’-1.5’ diameter.
Lies close to Sagittarius Dwarf Spheroidal gx, discovered in 1994.
Palomar 11 19 45.2 -08 00 8.0 9.8 Aql This Palomar gc appears as a diffuse, irregular glow 4’ SSE of a mag 9 star.
Try to resolve at high power.
Palomar 12 21 46.5 -21 15 2.9 11.7 Cap Irregular 3’ glow close NNW of 3 mag 12 stars.
May have been captured from the Sagittarius Dwarf Spheroidal gx

Further Reading

4) Local Group Dwarf Galaxies

Object RA Dec Size Mag Const Notes
WLM System 00 01.9 -15 27 11.5x4.0 10.6 Cet WLM system is a difficult, very low contrast galaxy spread out over 10’x5’, elongated N-S without central concentration
IC 10 00 20.4 +59 18 6.3x5.1 11.0 Cas Large, low surf br hazy region with no concentration and a mag 13 star superimposed.
Only 4° from the galactic plane.
NGC 147 00 33.2 +48 30 13.2x7.8 9.5 Cas Satellite system of M31 with a very low surface brightness
NGC 185 00 39.0 +48 20 11.7x10.0 9.2 Cas Relatively bright and large satellite system of M31.
Its brightest gc is only mag 16.5 and located 8’ N of center.
IC 1613 01 04.8 +02 07 16.2x14.5 9.2 Cet The Cetus system appears as an irregular hazy region with a brighter section to the NE .
Ursa Minor Dwarf 15 08.8 +67 11 41x26 10.9 UMi Very tough dwarf elliptical with extremely low surf br.
Look for subtle brightening in a low power field.
Draco Dwarf 17 20.2 +57 55 35.5x24.5 10 Dra The Draco Dwarf is a large, very low surf bright member of the Local Group,
~15’x10’, with several stars superimposed
SagDIG 19 30.0 -17 41 3.2x1.5 15 Sgr The Sagittarius Dwarf Irregular is a difficult 3’ roundish glow nestled in a rich Milky Way field.
Very difficult to identify.
NGC 6822 19 45.0 -14 48 15.5x13.5 8.8 Sgr Barnard’s Galaxy has a low, irregular surf br, ~14’ in length.
Use OIII filter to search for 2 small HII regions at N end.
Pegasus Dwarf 23 28.6 +14 45 5.0x2.7 12.6 Peg The Pegasus dwarf is just a very low surf br hazy region with no concentration, roughly 4’x2’.

Further Reading

5) Compact galaxy groups

Object RA Dec Size Mag Const Notes
Hickson 61 12 12.3 +29 11   12.2 Com "The Box" consists of 4 galaxies - NGC 4169, 4173, 4174, 4175 - forming a rectangle with sides 2.5’ by 1.5’.
Hickson 68 13 53.4 +40 17   11 CVn One of the best Hicksons contains NGC 5350, 5353, 5354, 5355, 5358.
Easy to locate 5’ SE a mag 6.5 star.
Seyfert's Sextet 15 59.2 +20 46   14.3 Ser Seyfert’s Sextet is NGC 6027, an extremely compact group!
Use high power to resolve 3 individual members.
Hickson 82 16 28.4 +32 51   13.6 Her Hickson 82 consists of the trio NGC 6161, 6162, 6163 within 2.7’.
A 4th 16 mag galaxy is close to 6161.
Shakhbazian 16 16 49.2 +53 25   14.6 Dra 5 extremely faint mag 15-16 galaxies in a 3.5’ chain.
View is severely hampered by a mag 9 star just 2’ NE!
Shakhbazian 166 16 52.8 +81 38   14.9 UMi Remarkable group of 5 or more extremely faint galaxies in a 7’ chain.
Located 30’ SE mag 4.2 Epsilon Ursa Minoris
Hickson 86 19 52.1 -30 49   13.1 Sgr ESO 461-007 is the brightest of 4 galaxies within 3’.
Use high power to resolve.
Hickson 90 22 02.1 -31 59   11.4 PsA Bright quartet containing the interacting system NGC 7174 and 7176, along with NGC 7172 and 7173.
Stephan's Quintet 22 36.1 +33 57   12.6 Peg A 6" can resolve 3 gxs in Stephan’s Quintet and a 10" or 11" may resolve all 5 members.
Located 30’ SSW of N7331.
Hickson 97 23 47.4 -02 18   12.9 Psc Quartet of IC galaxies with brightest member IC 5357 .
Other members include IC 5351, 5356, 5359.

Further Reading

6) Arp interacting pairs

Object RA Dec Size Mag Const Notes
Arp 144 00 06.4 -13 25 0.9x0.5 13.9 Cet Double system containing elongated NGC 7828 and an extremely compact companion, NGC 7829 just off SE end.
Arp 112 00 01.4 +31 26 1.2x0.9 13.3 Peg Arp 112 consists of a close interacting pair of small galaxies, NGC 7804 and 7805, less than 1’ between centers.
Arp 84 13 58.6 +37 26 2.9x1.5 11.4 CVn NGC 5394 and 5395 form a contact pair.
Look for a very faint dust lane and arm on the W side of NGC 5395 .
Arp 199 14 17.0 +36 34 0.9x0.9 13.4 Boo Consists of NGC 5545, a very elongated streak, with a very small companion (NGC 5544) attached at the SW end.
Arp 90 15 26.1 +41 41 1.8x0.7 12.2 Boo Nearly merged double system with NGC 5929 and 5930 in contact (just 34" separation between centers).
Arp 91 15 34.5 +15 12 1.7x1.3 12.1 Ser Bright double system forms a striking double with NGC 5953 and 5954 attached at NE edge, just 46" between centers.
Arp 293 16 58.5 +58 56 1.3x1.2 13.3 Dra NGC 6286 is the brighter edge-on with a smaller companion, NGC 6285, just 1.5’ NW.
Arp 81 18 13.0 +68 21 2.1x0.8 13.1 Dra Double galaxy in a common envelope consisting of NGC 6621 and 6622 just 40" between centers.
Arp 93 22 28.6 -24 50 2.3x1.4 11.9 Aqr NGC 7285 is the NE member of a double system with NGC 7284. The close pair is just 30" between centers.
Arp 284 23 36.2 +02 09 1.9x1.4 12.5 Psc Just 4’ NW of a mag 5.7 star is a 1.8’ pair with brighter NGC 7714 and a faint edge-on, NGC 7715.
Arp 86 23 47.1 +29 29 0.8x0.5 12 Peg This is a M51-type system with brighter gx NGC 7753 and fainter NGC 7752 2’ SW attached at the end of a spiral arm.

Further Reading

7) Abell Galaxy Clusters

Object RA Dec Size Mag Const Notes
Abell 262 01 52.7 +36 09 120 13.3 And Relatively loose Abell with over 50 galaxies visible in an 18-inch.
Core includes NGC 703, 704, 705, 708, 709, 710.
Abell 347 02 25.8 +41 53 40 13.3 And Brightest members NGC 906, 910, 911, 912 strung out on a 20’ string.
Located 30’ SW of NGC 891
Perseus GXCL 03 18.6 +41 31 30 12.5 Per Rich Perseus cluster with brightest gx NGC 1275, lies in a rich Milky Way field.
300 galaxies observed by Albert Highe
Hydra I GXCL 10 36.8 -27 32     Hya One of the nearest and easily viewed rich clusters.
Core includes NGC 3308, 3309, 3311, 3312, 3314, 3316.
Leo GXCL 11 44.5 +19 50 30 13.5 Leo One the richest clusters for amateurs.
Core incudes NGC 3837, 3840, 3841, 3842, 3844, 3845, 3851.
Coma I GXCL 12 59.8 +27 59 120 13.3 Com The richest cluster for amateurs.
Center on the two brightest members, NGC 4872 and 4889 and then enjoy the view.
Cor Bor GXCL 15 22.7 +27 43 30 15.6 CrB At 1 billion light years, the most distant cluster visible in an 18-inch scope and one of the most challenging!
Hercules GXCL 16 05.1 +17 45 40 13.8 Her Rich, irregular cluster, ~500 million l.y.
Includes NGC 6040, 6041, 6042, 6043, 6045, 6047, 6050, 6054.
Abell 2197 16 28.2 +40 54 60 13.9 Her Includes NGC 6146, 6160 and 6173 as well as 6145, 6147, 6150, 6174, 6175, 6180, 6184.
Abell 2199 16 28.6 +39 31 40 13.9 Her Swarm of faint, dimunitive galaxies surrounding giant cD galaxy NGC 6166.
Abell 4038 23 47.7 -28 08   12.6 Scl Brightest member, IC 5358, located 16’ W of Delta Scl (V = 4.5).
Nearby is IC 5353, IC 5354 and PGC 72436

Further Reading

8) HII regions in External Galaxies

Object RA Dec Size Mag Const Notes
NGC 55’s knots 00 14.9 -39 12     Scl Near the "core" of NGC 55 are 2 small HII knots (labeled as M3 in Alvin’s atlas, see below).
More faint knots are along the fainter E end.
NGC 253’s knots 00 47.6 -25 17     Scl Remarkable dust structure and mottling, particularly on the SW extension where 3 faint HII knots are visible.
NGC 604 in M33 01 34.5 +30 47 1.9x1.2   Tri Bright HII region on NE end of M33. A dozen more HII regions incl NGC 588, 592, and 595. Look here and here for more.
NGC 2363A in NGC 2366 07 28.9 +69 13 0.4   Cam At the SW end of the low surf bright gx NGC 2366, is a very bright HII knot , ~15" in size.
Try a UHC filter. It’s actually a double knot with a second, smaller and fainter piece just off the east end.
NGC 2404 in NGC 2403 07 37.1 +65 42     Cam Brightest of several HII regions in NGC 2403. Located close E of core along northern spiral arm, 1.5’ from the center. See also March 2013 issue of Sky & Telescope, “Celestial Fireworks”.
M 108’s knots 11 11.5 +55 40     Cam A few brighter patches or knots are visible along the major axis of M108 with a prominent HII knot along the W side.
NGC 4401 in NGC 4395 12 25.9 +33 32     CVn Brightest of several HII knots in NGC 4395, located ~2’ SE of the ill-defined core. Appears as an irregular 25" knot.
HK 15 in NGC 4449 12 28.2 +44 06     CVn Several giant HII regions are visible, the brightest ([HK83] 15) is a well-defined patch on the N edge of the gx, 1.5’ from the center.
Mrk 59 in NGC 4861 12 59.0 +34 51 0.35x0.30   CVn High surf br 15" knot at the SSW end of NGC 4861. Appears more prominent than the low surface brightness galaxy!
NGC 5471 in M101 14 04.5 +54 24 0.9x0.7   UMa Highest surf br of many HII regions in M101 on NE end. Also NGC 5447, 5449, 5451, 5453, 5455, 5458, 5461, 5462. See also Howard Banich’s article in Sky & Telescope June 2013 issue.
IC 1308 in NGC 6822 19 45.1 -14 43 1.0x0.9   Sgr Following of 2 HII regions at the N end of Barnard’s galaxy. A mag 12 star lies 2’ SE. Mild contrast gain with OIII filter. See also: feature on Barnard’s Galaxy and Dave Tosteson’s article in Sky & Telescope August 2023

Further Reading

9) Ancient, Giant Planetaries

Object RA Dec Size Mag Const Notes
EGB 1 01 07.2 +73 33 300"x180"   Cas Challenging planetary involved with a group of faint stars.
Use an OIII filter and low power.
HFG 1 03 03.8 +64 54 523" 12 Cas This huge, ancient pn has an extremely low surf br, perhaps 8’ in diameter.
HDW 2 03 11.0 +62 48 340"   Cas Large, very low surface brightness glow surrounding 3 mag 11 stars, ~4’ in diameter.
Use OIII filter and low power.
Abell 39 16 27.5 +27 54 170" 12.9 Her Relatively bright Abell planetary at least 2.5’ in diameter!
Use an OIII filter.
Sh 2-68 18 25.0 +00 52 475"x330" 11.2 Ser Huge low surface brightness glow, perhaps 5’-6’ in diameter with an OIII filter.
Sh 2-71 19 02.0 +02 09 124"x75" 12.3 Aql Large, interesting PN with an OIII filter.
Faint extension on S side and irregularities in the rim.
Abell 61 19 19.2 +46 15 201" 13.5 Cyg Large Abell pn spans 2.5’-3.0’ in diameter and irregularly lit. Situated in a rich Milky Way field.
Abell 65 19 46.6 -23 09 134"x34" 13.8 Sgr Relatively bright Abell pn, noticeably elongated NW-SE, appears similar to a low surf br gx.
Abell 72 20 50.1 +13 33 134"x121" 12.7 Del Large, 2’ disc with a mag 8 star just off the WSW edge!
Jones 1 23 35.9 +30 28 314" 12.1 Peg Huge annular planetary with 2 brighter arcs in the rim along the NNW and SSE sides giving a horseshoe shape.
Abell 84 23 47.8 +51 24 147"x114" 13 Cas Look for a 2’ disc with an OIII filter with a star embedded on the E side.

Further Reading

10) Quasars

Object RA Dec Size Mag Const Notes
APM 08279+5255 08 31.7 +52 45 Stellar 16.0 Lyn This mag 16 "star" is a superluminous QSO at a redshift of z = 3.9.
Distance of ~12 billion l.y!
Q0957+561 10 01.3 +55 54 Stellar 16.5 UMa Gravitationally lensed twin quasars is 15’ NNW NGC 3079.
Components mag 16.5 and 16.7, separated by just 6".
HS 1046+8027 10 50.6 +80 12 Stellar 15.0 Dra Relatively bright and nearby quasar (z = 0.12) discovered in 1999 and visible as a mag 15.0 "star".
Mrk 205 12 21.7 +75 19 Stellar 14.5 Dra Markarian 205 is a 14.5-15 "star" 1’ S of NGC 4319.
Arp redshift controversy with possible bridge to NGC 4319.
3C 273 12 29.1 +02 03 Stellar 12.9 Vir Brightest quasar, relatively nearby at ~2 billion l.y.
Appears as a mag 13 star in a triangle with mag 13.5 and 15 stars
SBSS 1425+606 14 26.9 +60 26 Stellar 15.8 UMa Very distant
mag 15.8 quasar (z = 3.165!) at a distance of roughly ~11.6 billion l.y.
PG 1634+706 16 34.5 +70 32 Stellar 14.7 Dra Mag 14.7 "star" 1.6’ SE of a mag 13 star. This is a luminous, distant qsr with z = 1.34
(~8.9 billion l.y.)
PG 1718+481 17 19.6 +48 04 Stellar 14.6 Her Mag 14.5 qsr at z = 1.08 and a light travel time of ~8 billion l.y.
Forms S vertex of a small triangle with 2 mag 13 stars.
HS 1946+7658 19 44.9 +77 06 Stellar 15.9 Dra Superluminous mag 16 qsr at a distance of ~11.5 billion l.y.
A nearby mag 16 star confuses the identification.
PHL 1811 21 55.0 -09 22 Stellar 14.0 Cap Recently discovered qsr (2001) is the 2nd brightest known at B = 13.9.
At z = .19 is 20% more distant than 3C 273.

Further Reading